1. Field of the Invention
The present invention relates generally to the field of fiber optics, and particularly to advantageous aspects of systems and methods for reducing splice loss in optical fibers.
2. Description of Prior Art
Optical fibers are thin strands of glass designed to carry optical signals long distances at high bandwidth. Optical fibers are typically cylindrically symmetric structures, including an inner xe2x80x9ccorexe2x80x9d region and an outer xe2x80x9ccladdingxe2x80x9d region. One or both of these regions are typically doped with various chemicals to alter the glass properties. Modern high performance optical fibers can contain several distinct annular regions each doped with different chemicals at various concentrations.
Optical fiber fusion splicing is important for achieving high quality joints between optical fibers. In this context, quality includes low loss, high strength, and superior long-term reliability. Optical fiber fusion splicing is distinguished from simple mechanical splicing in that in a fusion splice the fiber tips are melted together and form a welded joint. Many different heat sources have been developed for fusion splicing including chemical flames, high intensity laser beams, electric arcs, and resistive filament heaters. There is a wide variety of commercially available optical fiber fusion splicing equipment utilizing these techniques. Many of these commercially available devices can readily achieve in conventional single mode fiber (SMF) splicing having extremely low-loss,  less than 0.02 dB, and high-strength,  greater than 100 kpsi proof test. However, the processing conditions required for achieving high-quality optical fiber fusion splices depend upon the fiber design.
Current optical fiber networks, and networks under development, commonly require the use of specialty optical fibers, termed xe2x80x9cdispersion-managed fibers,xe2x80x9d which comprise many distinct annular layers and are strategically deployed in the optical network to control the dispersion of optical signals. Examples of such dispersion-managed fibers include dispersion compensating fiber (DCF) and inverse dispersion fiber (IDF). High performance optical networks require a large number of splices between dispersion-managed optical fibers. For example, in certain applications it is advantageous to alternate relatively short sections (xcx9c30 km) of dispersion-managed fibers over a relatively long distances (xcx9c1000 km). The large number of splices required for this application places stringent demands on the quality of the optical fiber fusion splices.
Recent experience has demonstrated that it is extremely difficult to achieve low-loss fusion splices between certain high performance dispersion-managed fibers. For example, the fusion splicing processing conditions that would result in less than 0.02 dB of splice loss in standard SMF result in greater than 0.5 dB splice loss when joining DCF or IDF to each other or to SMF. These high splice losses restrict the applications of such dispersion-managed fibers and limit the design possibilities for an optical network since network performance degrades as the number of dispersion managed fiber splices is increased.
There is thus a need for systems and methods for reducing splice loss for these and other types of optical fibers.
Aspects of the invention provide systems and methods for reducing splice loss in an optical transmission line. A system according to an aspect of the invention includes fiber guides for holding a first fiber and a second fiber in position for splicing to each other at a splice point. A heat source applies sufficient heat at the splice point to cause the first and second fibers to be fused together at the splice point and subsequently applies heat to the splice point after the splice has been completed. The system further includes a tensioning assembly for applying a controlled, non-zero tension to the first and second fibers after they have been spliced together.
Additional features and advantages of the present invention will become apparent by reference to the following detailed description and accompanying drawings.